Expansible piston



Feb. 16, 1943. w. G. swlF'T 2,311,584

EXPANSIBLE PISTON Filed Nov. 25, 1941 2 Sheets-Sheet 1 Patented Feb. 16,1943 UNETED STATES i ATEN'i' GFFICE EXPANSIBLE PISTON Walter G. Swift,Flint, Mich.

Application November 25, 1941, Serial No. 426,416

4 Claims.

This invention relates to pistons.

An object of this invention is to provide a piston structure including aring carrying head formed with depending wrist-pin bosses or bearings,and a split expandible skirt removably secured to and encompassing thebosses.

Another object of this invention is to provide a piston with anexpandible split skirt which is removably mounted on the head or body ofthe piston, so that it will not be necessary to replace the piston whenthe cylinder becomes worn and new rings are inserted in the grooves ofthe piston.

A further object of this invention is to provide in an expandible pistonskirt an improved adjusting means so that the amount of expansion orenlargement can be accurately gauged withut the use of calipers or amicrometer, the adjusting means including a calibrated screw andgraduations correlated with the skirt so that turning of the adjustingand holding screw will efiect expansion or contraction of the skirt inthe desired amount.

A further object of this invention is to provide in an adjusting meansof this kind an improved means for locking the adjusting screw in itsadjusted position so as to prevent expansion of the skirt underoperating conditions.

To the foregoing objects and others which may hereinafter appear, theinvention consists of the novel construction, combination andarrangement of parts as will be more specifically referred to andillustrated in the accompanying drawings, but it is to be understoodthat changes, variations and modifications may be resorted to which fallwithin the scope of the invention as claimed.

In the drawings:

Figure 1 is a detail side elevation of a piston constructed according toan embodiment of this invention,

Figure 2 is a detail bottom plan of the piston,

Figure 3 is a sectional view taken on the line 3-3 of Figure 1,

Figure 4 is a sectional view partly broken away taken on the line 4-4 ofFigure 1,

Figure 5 is a sectional view taken on the line 5-5 of Figure 4,

Figure 6 is a fragmentary side elevation of the lower portion of thepiston,

Figure 7 is a fragmentary sectional view taken on the line l'! of Figure1, and

Figure 8 is a fragmentary sectional view taken on the line 88 of Figure7.

Referring to the drawings the numeral I0 the skirt designates generallya piston structure which includes a head H and a skirt portion I2. Thehead I! is formed with a top wall l3 and a cylindrical side wall M whichis formed with a plurality of ring receiving grooves 15. The side wall[4 is also formed with diametrically opposed oil passages or openings I6which communicate with the oil ring receiving groove I5 in the lowerportion of the side Wall l4.

The head H has formed integral therewith a pair of depending wrist-pinreceiving bosses or bearings l! which extend below the cylindrical wall14 and which are dependingly supported below the wall [4 by pairs ofvertically disposed ribs l8. The ribs I8 extend upwardly to the top walll3, and a pair of upper parallel ribs #9 are formed integral with thetop wall l3 and also with the depending ribs I8. The outer ends of thebosses or bearings I! are inwardly offset from the peripheral surface ofthe side wall [4, and the skirt I2 snugly engages about the outer endsof the bearings 20. The peripheral surface of I2 is substantially flushwith the peripheral surface of the side wall [4.

The skirt [2 includes a cylindrical body 2! which is longitudinallysplit as at 22. The skirt 2| is formed of resilient material and is of aconstruction such that the skirt 2| will normally expand in order thatthe exterior diameter-of the skirt 2! may, as hereinafter described, beadjusted to the desired diameter for sliding contact with the surface ofthe cylinder wall. The skirt i2 has formed integral therewith a pair -ofdiametrically disposed inwardly projecting flanges 23 which are adaptedto engage against seats 24 which are formed at the lower ends of thebearing bosses H. The flanges 23 are of segment shape in plane and areeach provided with a pair of openings 25 through which fastening devices26 are threaded into threaded openings 21 which are formed in thebearings I1, and a resilient spring washer 28 is interposed between thehead of each fastening device 26 and the adjacent side of the flange 23.The flange 23 is also provided with a recess 29 within which the springwasher 28 is adapted to snugly engage as shown in Figure 4.

The kirt body 2| on opposite sides of the split portion 22 thereof hasformed integral therewith a pair of confronting and parallel cars 33 and3|. The cars 30 and 31 extend inwardly from the inner side of the skirt2! on opposite sides of the split portion 22 thereof, and a cap screw orfastening device 32 is extended through an opening 33 formed in the ear3|, and is threaded into a.

' the recess 36.

threaded opening 34 which is formed in the ear 3!). In order to provideameans whereby the fastening or skirt adjusting member 32 may be lockedin its adjusted position, I have provided a bolt or screw clamping block35 which is seated in a recess 36 formed in the lower side of the car30. The threaded opening 34 communicates with the recess 36 at thebottom of the recess so that the upper side of the block 35 will contactwith the threads of the bolt or fastening device 32.

The recess 36 as shown in Figures 2 and 7 is formed with parallel sides31 and rounded ends 38. The block 35 has a configuration substantiallycoincident with the configuration of the recess 36 and is adapted toloosely engage within A clamping screw or bolt- 39 is threaded into theear 3% and extends loosely through an opening 49 which is formed in theclamping block 35. Tightening of the screw or bolt 39 will placepressure on the block 35 and cause this block 35 to tightly bear againstthe threads of the screw or bolt 32.

The bolt or screw 32 is adapted to be tightened or loosened by means ofa tool which may be extended through an elongated opening 45 which isformed in' the skirt wall 2i. The belt or screw 32 is preferably soconstructed that when it is turned in either direction to either loosenor tighten the skirt 2! with respect to the cylinder of the engine, theworkman can accurately deter; mine the amount of expansion orcontraction. This is accomplished by providing the outer face 42 of theear 3! with a plurality of radially arranged graduations 53 having'indicia' 54 stamped thereon. The head 45 of the fastening device 32 isprovided with a pointer 43 correlated with the graduations 43 andindicia til, so that when a tool such as a screwdriver or the like, isinserted in the kerf it! of the screw 32, the screw may be turned in thedesired direction and for the desired amount to effect a predeterminedexpansion or contraction of the skirt wall 2|.

In the use and operation of this piston structure the piston head It isadapted to have the desired rings mounted the grooves l and I5 thereof,and the wrist-pin at the upper end of the connecting rod is adapted toengage in the bearing bosses ll. The skirt I2 is secured by thefastening devices 26 to the lower ends of the bearings I '1', and theopenings 25 for the fastening device 26 are preferably substantiallylarger in diameter than the outside diameter of the screws The purposefor these larger openings 25 is to permit the desired expansion orcontraction of the skirt l2. In the event it is desired to expand theskirt 12, in order that this skirt may snugly and slidingly engage theinner surface of the engin cylinder wall, the clamping screw or bolt 39is loosened, thereby relieving the adjusting screw 32 from pressure fromthe clamping block 35. The adjusting screw 32 may then be turned in acounterclockwise direction, thereby permitting the skirt 2| to expandfor the desired distance. The amount of expansion of the skirt 2| may bedefinitely and accurately determined .by th position of the pointer 46with respect to the graduations 43 and the indicla, 44 which are carriedby the outer side of the ear 3|.

With a piston structure as hereinbefore described it is possible toprovide for replacement of the skirt portion of the piston withoutreplacement of the head portion of the piston, and in the event largerrings are inserted in the ring grooves l5 and I5 due to wear of theprior rings and Wear of the side wall 12 of the piston together withwear of the cylinder wall, the piston slap in the cylinders may beeliminated by expansion of the skirt 2 I as hereinbefore described, orby complete replacement of the skirt, if such procedure should benecessary or desirable.

What I claim is:

1. A piston comprising a grooved head, a pair of wristpin bearings,means dependingly'supporting said bearings from-'said 'head, a resilientsplit expandible skirt encompassing j-said bearings, a

- pair of diametrically opposed inwardly projecting flanges integralwith said skirtgmeans 'detachably securing said skirt to said bearings,a pair of opposed inwardly projecting 'ea'rs carried by said skirt onopposite sides of 'the'split portions thereof, and means engaging saidears for holding said skirt in a predetermined expanded position.

2. In a piston having a head, a removable split skirt, means removablysecuring the skirt "on the head, said skirt including a resilientlyexpansible split skirt body, 'a pair of parallel inwardly proing throughone of said ears and threaded into the'other ear for regulating theexpansion of said skirt, and means for locking said latter means againstmovement.

4:. In a piston having a head, a removable split skirt, means removablysecuringuthe skirt on the head, said skirt including a resilientlyexpansible split skirt body, a pair "of parallel inwardly projectingears carriedby said skirt on opposite sidesof the split portion thereof,an expansion regulating screw loosely engaging through one ear andthreaded into the other ear, graduations carried by the outer side ofsaid one ear, and a pointer carried by said screw whereby the 'degree ofexpansion may be accurately determined.

WALTER Gr SWIFT.

